Dunning, in her 30s, says the island started her conservation journey - she's worked for the Department of Conservation for the past 11 years.
She's been on Tiritiri for 12 months now and says it's "a really special place".
"Revegetation is doing really well, and the bird population numbers are amazing. All the people that come out here are so passionate about it and so willing to share knowledge.
You don't need to be a bird expert to spot kereru, fantails, kiwis and penguins here - the island is a haven for native birdlife.
Rats and pests were eradicated from the island in the 1990s, and since then the number of birds has massively increased.
As a result, it's become popular with bird watchers - and anyone after a stunning view of the Hauraki Gulf.
Supporters of Tiritiri Matangi shop and guiding manager Mary-Ann Rowland says the island is different from other bird sanctuaries because the birds are so easy to spot.
"We're lucky to be able to see the birds really easily, it's a really special place to come and see them doing what they do. We band the chicks and keep an eye on them, something we wouldn't be able to do in the big forests on the mainland."
Rowland has been working with the supporters group for almost 12 years and previously worked as a guide on the island. She's also lived on the island from Wednesday to Sunday every week for almost 12 years.
Rowland says the DoC-owned bunkhouse where visitors can stay overnight is always full over summer and it's a great opportunity to experience waking up with the wildlife.
"You'd be hard-pressed to get a bed there over summer, but it's also great to come during the winter – it's quieter and the experience is just as amazing."
"It's great for families and people of all ages and we see a lot of tourists come through as well."
The island also sees about 7000 school groups come through each year as part of an initiative to bring groups from low-decile schools to visit the island.
There's a limit of 170 paying passengers on each ferry.
Around 32,000 people a year visit via the ferry and around 3000 others come on their own boats.
Tiritiri is a great place to bring the whole family to learn more about native birds from some stunning vantage points – a conservation haven just over an hour away from Auckland.
Tiritiri Matangi
Location: Hauraki Gulf, 3.4km east of the Whangaparaoa Peninsula and 30km northeast of Auckland
How to get there: A 75-minute ferry trip from central Auckland or only 20 minutes if you catch the ferry from Gulf Harbour on the Whangaparaoa Peninsula
Highlights: Guided tour, school trips, stay overnight in a DoC bunkhouse, experience native birdlife, or visit the 150-year-old lighthouse